text: const assert      = require('assert');
  const del         = require('del');
  const eslint      = require('gulp-eslint');
  const exec        = require('gulp-exec');
  const File        = require('fs');
  const gulp        = require('gulp');
  const gutil       = require('gulp-util');
  const sourcemaps  = require('gulp-sourcemaps');
  const babel       = require('gulp-babel');
  
  // gulp clean -> clean generated files
  gulp.task('clean', function(done) {
    return del(['lib']);
  });
  
  // gulp lint -> errors if code dirty
  gulp.task('lint', function () {
    return gulp.src([ 'src/**/*.js', 'test/*.js' ])
      .pipe(eslint())
      .pipe(eslint.formatEach())
      .pipe(eslint.failOnError());
  });
  
  gulp.task('compile', function() {
    return gulp
      .src('src/**/*.js')
      .pipe(sourcemaps.init())
      .pipe(babel())
      .pipe(sourcemaps.write('.'))
      .pipe(gulp.dest('lib'));
  });
  
  // gulp build -> compile coffee script
  gulp.task('build', gulp.series('clean', 'lint', 'compile'));
  
  
  // gulp watch -> watch for changes and compile
  gulp.task('watch', gulp.series('build', function() {
    return gulp.watch('src/*.js', gulp.series('clean', 'build'));
  }));
  
  // gulp -> gulp watch
  gulp.task('default', gulp.series('watch'));
  
  // Generate a change log summary for this release
  // git tag uses the generated .changes file
  gulp.task('changes', function() {
    const version   = require('./package.json').version;
    const changelog = File.readFileSync('CHANGELOG.md', 'utf-8');
    const match     = changelog.match(/^## Version (.*) .*\n([\S\s]+?)\n##/m);
  
    assert(match, 'CHANGELOG.md missing entry: ## Version ' + version);
    assert.equal(match[1], version, 'CHANGELOG.md missing entry for version ' + version);
  
    const changes   = match[2].trim();
    assert(changes, 'CHANGELOG.md empty entry for version ' + version);
    File.writeFileSync('.changes', changes);
  });
  
  // gulp tag -> Tag this release
  gulp.task('tag', gulp.series('changes', function() {
    const version = require('./package.json').version;
    const tag     = 'v' + version;
  
    gutil.log('Tagging this release', tag);
    return gulp.src('.changes')
      .pipe( exec('git add package.json CHANGELOG.md') )
      .pipe( exec('git commit --allow-empty -m "Version ' + version + '"') )
      .pipe( exec('git tag ' + tag + ' --file .changes') )
      .pipe( exec('git push origin ' + tag) )
      .pipe( exec('git push origin master') );
  }));
  
  
  
  